Unseen dangers from the Japanese tsunami may linger for decades

The debris from the tsunami which struck eastern Japan two years ago today could still be washing up on the western seaboard of Canada and the United States decades from now with, as yet, unknown consequences for marine life.

Debris from the Japanese tsunami last year.

Video screen capture

Two years ago today, on March 11, 2011, communities along the east coast of Japan were Japan was struck by one of the most destructive tsunamis ever recorded. In Japan, as a result of the meltdowns of reactors which occurred at the Fukushima Nuclear Plant they will be living with the consequences for generations. Even today, as Digital Journal reported last week, over 300,000 Japanese were made homeless by the tsunami or have not been able to return to their homes due to radioactive contamination.

But the effects of the Japanese tsunami will also continue to be felt right across the Pacific basin for years to come as a result of the colossal amounts of debris washed into the sea.

According to Japanese estimates, approximately 5 million tonnes of debris was washed into the Pacific by the backwash from the tsunami. Debris comprised everything imaginable from cargo containers to floating docks but it is the smaller debris, interacting with sunlight and ocean waves and currents, which may pose a more serious long term problem for communities that rely on the ocean for their livelihood.

From the assortment of garbage that was clawed into the ocean as the waters of the Japanese tsunami receded, according to official Japanese estimates, some 3.5 million tonnes sank immediately, leaving, according to Global Post, a floating garbage dump of 1.5 million tonnes comprising plastic, timber, fishing nets, shipping containers, industrial detritus and other non-submersible objects.

Speaking to the New Straits Times, a spokesman for French environmental group, Robin des Bois which is studying the problem of tsunami debris, said, ““In a single stroke, the tsunami dumped 3,200 times the amount of rubbish that Japan discharges annually into the Pacific. In plastic alone, the volume is the equivalent to several decades of accumulated waste in the Atlantic and Pacific.”

Quite apart from the large items of floating debris posing a navigation hazard to shipping and marine mammals, the miasma of floating garbage has the potential to cause problems as a result of non-native species ‘hitching a ride’ to the other side of the Pacific. In addition, as the garbage begins to degrade, there is a risk to ecosystems and the food chain as a result of infinitely ground down nano-particles being consumed by wildlife.

In early 2012, lightweight debris, like polystyrene and wood, easily pushed along by prevailing winds started washing up along the shorelines of Alaska, Oregon, Washington state and British Columbia. Such debris is easily spotted and removed although even then, there were warnings not to burn debris or save driftwood for fuel due to the risk of radioactive contaminants finding their way into the atmospheric, compounding the already serious problems at Fukushima.

There then followed larger slower items including in one case two massive concrete docks on styrofoam floats which had once formed part of the fishing port of Misawa in Japan. These arrived separately along the shores of Oregon and Washington eight months apart, reports Global Post. One of the docks had to be decontaminated with bleach when it was discovered that it was covered in species of algae and barnacles not indigenous to America’s east coast.

Marine debris accumulation locations in the North Pacific Ocean

NOAA

The likelihood is that a ‘drip-drip’ of Japanese tsunami debris will continue arriving on North America’s east coast for some time. As Sherry Lippiatt, regional coordinator in California for the United States National Oceanic and Atmospheric Administration's (NOAA) marine debris programme, quoted on Asia One, said, "NOAA's data suggests that the debris is no longer in a mass or a patch. Rather, it has spread out across the vast North Pacific Ocean since it was introduced nearly two years ago."

As the years go by, tracking the debris becomes more difficult. Rather than staying in a homogenous mass, the debris, with the action of waves, ocean currents and sunlight, starts to break down into smaller and smaller particles and adds to what was already a serious pollution in the North Pacific Ocean sometimes known as the Great Pacific Garbage Patch. But the North Pacific Garbage Patch isn’t like the local garbage dump. It’s an area of ocean which contains high concentrations of plastics, chemical sludge and other debris, trapped by North Pacific currents.

Tracking debris with the assistance of satellites eventually becomes impossible. When debris breaks down to particulate matter it becomes suspended in the water. At that stage, satellites cannot track where the micro-debris is headed. It is this invisible threat from the tsunami debris that is the most worrying and whose effects may continue to be felt for decades.

Simon Boxhall of Britain’s National Oceanography Centre has carried out a number of studies of the long term effects of plastics in the seas. In relation to the Japanese tsunami debris, speaking to Global Post, he said, “Most of it is pretty harmless,” with the obvious exception of debris tainted with radioactivity from Fukushima. But Boxhall was particularly concerned about plastics which have become degraded to micro-particles.

Plastic nanoparticles — the unseen legacy of the Japanese tsunami

In a recent BBC Science News article, Simon Boxhall focused on the effects of micro-plastics in the marine environment. Commenting on how plastic micro-particles are already in the food chain he said, “There's been a lot of research in the United States looking at how the plastic gets into the food chain, and certainly it's been shown that it gets into bi-valves, mussels and oysters on the seabed, and it does have an effect on them.”

He had no good news for fisheries and fishing communities along America’s west coast who, in the wake of the tsunami, are now facing the unknown effect of micro-plastics on fish and wildlife for generations. Boxhall explained that bi-valves bio-accumulate the microscopic particles of plastic as they filter water. In some cases, the concentrations of plastics has built up to such an extent that the molluscs are transformed into hermaphrodites. Previously, it had been assumed that these plastics would have a similar effect to roughage in humans, i.e. passing through the digestive system with no lasting effects, but scientists now know that these nano-particles of plastic can mimic sex changing hormones like oestrogen.

The problem of micro-plastics is compounded as they act like sponges, soaking up other dangerous contaminants. Boxhall gave, as an example, Tributyltin, an anti-fouling material, and a toxin, which had been found in micro-particles of plastic.

His conclusion emphasised that the violence of the Japanese tsunami witnessed two years ago today may now have transformed into an unseen, unknown threat to the environment in the years to come, saying, “The tiny plastic particles absorb these materials and effectively become quite toxic. We don't know yet whether that then has an impact on the human food chain. It's still very early days to find out how far up the food chains these plastic particles go."